Business Logic

In addition to field-level validation, there may be high-level custom business rules that involve different entities or concepts not expressible at the single column level, such as:

• If a product is discontinued, its UnitPrice cannot be updated

• An employee's country of residence must be the same as their manager's country of residence

• A product cannot be discontinued if it is the only product provided by the supplier  

http://msdn.microsoft.com/en-us/library/aa581779.aspx

• In the DataMapper pattern you have one domain object that holds all the business logic, for exmaple user.getLinkToProfile() (or something similar) but knows nothing about the database in question, in addition to this you have a mapper-object that is responsible for saving, updating, selecting, etc. user objects from the database which would have UserMapper::find(1), UserMapper.save(user)

  thr - http://stackoverflow.com/questions/93773/how-does-the-activerecord-pattern-differ-from-the-domain-object-or-data-mapper-p

A Service Layer defines an application's boundary [Cockburn PloP] and its set of available operations from the perspective of interfacing client layers. It encapsulates the application's business logic, controlling transactions and coor-dinating responses in the implementation of its operations.

http://martinfowler.com/eaaCatalog/serviceLayer.html

Operations such as account.AcceptTransaction(transaction) and account.CalculateCurrentBalance() are domain logic which should go on those very same anemic entities.

George Mauer - http://lostechies.com/jimmybogard/2009/12/03/persistence-model-and-domain-anemia/

Each interaction between a client system and a server system contains a certain amount of logic. In some cases this can be as simple as displaying information in the database. In others it may involve many steps of validations and calculations.

http://martinfowler.com/eaaCatalog/transactionScript.html

...your code should either be in the business of doing business logic or in the business of instantiating and wiring other objects together. What this effectively means is that your either have classes with ifs and loops (your business logic) or you have classes with new operators (your factories).  

http://misko.hevery.com/2009/03/30/collaborator-vs-the-factory/

 ...They might, for instance, when changing the sex of an employee, have to go over to the health insurance screen and mark that the person does not need prenatal care. That's what the software is supposed to do for you! That's business logic.

Gregg Young Presentation - http://skillsmatter.com/podcast/design-architecture/architectural-innovation-eventing-event-sourcing/